(a) Field of the Invention
The invention relates to a firm automatic multi-sectional collapsible umbrella structure, and more particularly, to a multi-sectional automatic collapsible umbrella having a minimal volume when collapsed and enabling a shaft thereof to steadily stretch the umbrella for usage.
(b) Description of the Prior Art
Umbrellas are people's daily commodities for shielding against the sun and/or rain, with conveniences and practicability thereof being long favored. To offer better portability, a shaft of an umbrella is often devised as a multi-sectional design, so that an overall volume of the umbrella is reduced when collapsed and the umbrella can thus then be stored and carried in a more handy manner. To satisfy expanding market demands as well as to provide users with further conveniences, umbrella manufacturers later proposed an automatic multi-sectional collapsible umbrella as shown in FIG. 1.
Referring to FIG. 1, a current automatic multi-sectional collapsible umbrella 1 having automatic stretching capability comprises a cover 11, a multi-sectional shaft 12, a notch 13, an auxiliary runner 10, a runner 14, main ribs 15 and stretchers 16. Around the notch 13 is a plurality of pivotally disposed main ribs 15 for supporting the cover 11; around the auxiliary runner 10 is a plurality of pivotally disposed stretchers 16 for supporting the main ribs 15; and around the runner 14 is a plurality of pivotally disposed stretching ribs 18 for supporting the stretchers 16. The shaft 12 is in a multi-sectional form, and has an upper end thereof fixed to the notch 13. Within the multi-sectional tube of the shaft 12, and between the auxiliary runner 10 and the runner 14, are respectively provided with compression springs 32 and 31. When the umbrella 1 is collapsed, the shaft 12 is compressed and maintains as a shortened structure using a fastening device in a handle 19. Meanwhile, the compression spring 31 between the auxiliary runner 10 and the runner 14 is also set in a compressed state. When a trigger button at the handle 19 is triggered, the fastening device is instantaneously set free. The multi-sectional shaft 12 rapidly expands using elasticity of the compression spring 32 therein, and the auxiliary runner 10 and the runner 14 are instantaneously stretched using elasticity of the compression spring 31. Hence, through interlocking effects of the stretching ribs 18, the auxiliary runner 10 and the runner 14 are quickly sprung upwards to approach a place near and below the notch 13 to assist stretching the umbrella. To collapse the umbrella, the runner 14 is pulled downwards, and the umbrella can be entirely collapsed by overcoming elasticity of the compression springs 31 and 32.
Referring to FIG. 2 showing a elevational view, partially in section and with portions broken away of another multi-sectional collapsible umbrella capable of automatic stretching and collapsing movements, an umbrella 1A comprises a cover 11, a multi-sectional shaft 12, a notch 13, a runner 14, main ribs 15 and stretchers 16. Around the notch 13 is a plurality of pivotally disposed main ribs 15, and around the runner 14 is a plurality of pivotally disposed stretchers 16 for supporting the main ribs 15. The shaft 12 is a multi-sectional form, and has an upper end thereof fixed to the notch 13. The shaft 12 is further provided with a compression spring 31 therein, and between the runner 14 and the notch 13 is a connecting pull rope 4. The pull rope 4 has an outer end thereof connected to the runner 14, inserted through sliding wheels 131 and 132 at the notch 13, and a sliding wheel 133 at the runner 14; and the other end thereof inserted into the shaft 12, extended downward along the shaft 12, and connected to a fastening device at a handle 19. To stretch the umbrella, a button at the handle 19 is triggered to set free the fastening device, and the multi-sectional shaft 12 is then rapidly elongated using elasticity of the compression spring 31 therein. Meanwhile, a lower end of the pull rope 4 passes through the fastening device to be connected at the handle 19 while remaining immobile, such that the length of the pull rope 4 between the shaft 12 and the sliding wheel 131 at the runner 14 is gradually reduced, thereby lifting the runner 14 to approach a place near and below the notch 13 to complete stretching the umbrella. To collapse the umbrella, the button at the handle 19 is triggered, so as to first loosen the fastening device at the lower end of the pull rope 4. The pull rope 4 in the shaft 12 also becomes lax, and using a collapsing spring 161 for gathering the stretchers 16, the runner 14 is pushed to slide downward, thereby accomplishing automatic collapsing of the umbrella 1A.
According to the aforesaid descriptions, although the umbrellas 1 and 1A are capable of automatic stretching and collapsing movements the shaft 12, due to generally being two-sectional or multi-sectional designs, needs to be further devised into having more sections in order to provide the umbrella with a reduced overall volume. However, as the number of sections of the shaft 12 increases, it is inevitable that diameters of an innermost tube and an outermost tube thereof differ to a large extent. In addition, to prevent undesired wavering and deviations of the runner 14 and the auxiliary runner 10 when performing up-and-down movements at the shaft 12, the shaft 12 often has a section with a smallest outer diameter as it lower portion joined to the handle 19. Therefore, for that section of the shaft 12 with the smallest outer diameter, since its diameter is smaller than other section and thus relatively weaker in strength, bending and chipping are likely to result and thereby fail to steadily stretch the umbrella. Therefore, it is a vital task of umbrella manufacturers to provide an automatic multi-sectional collapsible umbrella, which has minimized overall volume and length and allows a shaft thereof to firmly support the umbrella to a stretched state when stretching the umbrella.